Police were trying to identify the vandals who knocked over or damaged at least 100 headstones at a Jewish cemetery in Philadelphia as the nation grappled Monday with yet another wave of anti-Semitic incidents.

Meanwhile, bomb threats forced the evacuations of Jewish Community Centers in New York and in 10 other states.

"When we got there, I saw the degree of desecration," Rabbi Yosef Goldman of Temple Beth Zion-Beth Israel in Philadelphia told NBC News after viewing the damage at Mount Carmel Cemetery. "Seeing it in person was heartbreaking and devastating..,You feel the violation."

"This is not just a random act," Rabbi Shawn Zevit of the Mishkan Shalom synagogue in Philadelphia told the local NBC affiliate. "To topple so many headstones clearly is a concerted effort with intent."

It's definitely disturbing to see people act like this.

It really makes no sense why someone would go through this trouble. Unless there's a connection between the 100 headstones, then what's the point?

I don't think there's a connection. If there is, then we sure have a mystery to solve.